Monitoring　the　marine　aquaculture　plays　an　important　role　in　the　management　of　marine　fisheries,　and　also　provides　a　valid　method　to　evaluate　the　expansion　intensity　of　the　mariculture.　In　this　context,　different　periods　(2003,　2005,　2008,　2011,　2013,　2014　and　2016)　of　Landsat　satellite　data　were　collected　and　supervised　classification　method　support　vector　machine　(SVM)　method　was　applied　to　extracted　marine　aquaculture　in　the　Sansha　Bay.　Finally,　different　expansion　indicators　were　used　to　evaluate　the　expansion　intensity　of　mariculture　in　the　study　area.　The　results　showed　that:　(1)　the　area　of　cage　and　algae　culture　increased　rapidly,　with　the　annual　rates　of　expansion　in　2.2x10(4)　km(2)　and　9.3x10(4)　km(2)　respectively　from　2003　to　2016;　(2)　The　total　marine　aquaculture　reached　160x10(4)　km(2)　in　2016,　more　than　21.2%　of　the　planned　mariculture;　(3)　Cage　culture　expanded　from　the　coast　of　mainland　and　island　to　the　deep　sea,　but　the　algae　culture　expanded　more　obviously　and　almost　covered　the　sea,　and　the　expansion　intensity　of　cage　and　algae　culture　varied　greatly　at　different　periods.